This is my fist headphone amp, so I don't have anything to compare it to. I have the Sennheiser HD598 headphones and my first generation Microsoft Zune had a tough time giving them enough power. The CMoyBB makes a huge difference! I can now listen to music as loud, and louder, than I want to. The CMoyBB could easily blow my headphones if I wanted to, that's how powerful it is. There is no background noise, such as hissing or static, from the CMoyBB whatsoever. The bass boost adds the perfect amount of bass, which the HD598 is notorious for not having. JDSLabs customized the CMoyBB specifically to my HD598, however I'm sure the amp can still be used with any other headphones and still sound perfect. Highly recommend this amp!

Pros: small, cheap, bass boost & if ordered as 18v with a jumper can play any ohms cans

Cons: none that I can think of at the moment

great little tin of sweets - brings a new layer to familiar tracks when compared to straight from iPod. Nicely balanced sound with option of bass boost. Order the 18V for hi impedance cans and ask for a jumper to short the second battery terminal (making it a 9V amp) when listening to lower impedance cans. Only marked it down to 4.5 stars on quality because its an old sweet tin!!

Cons: A mint tin is not an enclosure everyone likes, bass boost is a bit muddy, not 100% robust

For a small portable amp in a tin you can't do any better than the JDS LABS cmoy. Ok it's slightly more expensive then some of the competition but the circuitry is professionally assembled and the overall quality of parts used is great. I opted for the 18v option and choose to replace the stock op amp with a AD8066 unit which suits my grado sr325is very well. I know the grados do not need to extra juice but this comes in handy when using different cans as well. Coupled with my Grados for a little portable system the sound is great and well balanced. I cannot recommend this amp highly enough for what it is. The bass boost feature is useful sometimes dependant on the genre of music and how it is mixed/mastered....in some instances it can "add depth" to some tracks. The only issues I've had is the input jack becoming faulty, I sent the amp back for repair and I must admit the customer service was great and I was informed this was a rare case of a faulty jack, since the amp has been returned I have had no further issues. The amp internally is very streamlined and quality components have been used, op amps are very much personal preference but I highly recommend trying the AD8066 out you won't be disappointed. I am considering buying another for my brother and would recommend this amp to anyone wanting a cheap portable solution.

Cons: Enclosure is not the sturdiest thing in existence (what would you expect)

A fantastic product, JDSLabs make some great CMoys, and the bass boost is fantastic from my point of view. Some may argue it is a bit muddy at higher volumes, but I rarely noticed it to an extreme extent, and even when I noticed it a bit, I remembered how cheap the amp was (also, never forget you can turn off the bass boost). If you don't like the "hipster-ish" look of it, or don't trust the enclosure, I know tons of people bought $10 enclosures and fit them in just fine. I'd recommend this in a heartbeat.

Like the title says, this CMoy from JDS is killer! Great sound in a small package for less than half of what many comparable amps cost. It adds a nice warmth and depth to the XBA 3s and GR07s I've tried. The 9V easily powers most headphones, even those that are harder to drive. The bass boost is rarely needed, but if you want some extra bump, the CMoy has plenty to go around.

Like many portable amps I was wary about the battery life, especially for something so inexpensive. No worries anymore. I has been playing since mid-morning and it is now 6:45. Also, the rechargeable battery will allow it to play while its charging - a serious step up over Fiio's amps.

The volume knob is very sensitive and the amp will turn off automatically if the headphone cable is disconnected. Great feature!

The only things I can imagine would bug some people (who shouldn't have ANY problems in this price range...) is that the Altoids tin is a little funny (although unmarked tins can be purchased). The lack of gain or impedance control has been mentioned but honestly for everything else you get, that's like missing the sprinkles, on the icing, on the cake.

Great portable amp for those on a budget. Amp arrived packaged really well and was shipped incredibly quickly to my country. Looking inside the tin, the circuit board and components appears to be constructed to high standards, though the front panel connectors on mine weren't aligned 100% but that is nitpicking.

I use the headphone amplifier with my Samsung Galaxy S at work and it drives my Sennheiser HD580s very nicely indeed! This little CMoy has good soundstage and bass on the default setting and a clean transparent sound. Highly recommended! The bass boost setting however does distort the sound a bit and muddies up the sound somewhat so I seldom use it. The unit also has a tendency to pick up interference from radios and other RF sources. I hope that newer versions might benefit from better shielding to prevent this.

I'm a bit scared that I might damage the casing one day as it looks pretty fragile. To prevent the casing from picking up scratches, I'm carrying the amp in a small sock that I once bought to protect an old ipod with which seems to do the trick. Batteries last surprisingly long, but they are expensive!

Most IEMs I own do not benefit or need an amp. A few do. The bass boost is just what my sonic taste needed from my RE 0 and Carvins. My Sansa Fuze needed a boost when I listen to my Sony headphones which was my main reason for the purchase. My Sony Walkman benefits from this amp as does my Cowon J3, the latter by the bass boost function. The build is first rate. It's an amp, it amplifies what needs amplifying. If there's junk you get louder junk, if it's clean than you get clean. It changes nothing from what's there and I think most people will appreciate the improved bass option at a budget price. JDS guys are all about help and service, I couldn't be more satisfied. I've had amps at three times the price but this is the one I'll hang on to.